Video conferencing has been in use for many years. In a video conference, several users dial into a conference at the same time or at different points of time. During the video conference, audio data and video data are transmitted to (and from) the user devices. The transmission of audio data and video data is typically done using streaming technologies.
Hypertext Transfer Protocol (HTTP) based streaming of multimedia content (including audio data and video data) is a newer technology with high momentum. HTTP based streaming can also be used to stream video conferences. As an alternative to HTTP, the streaming of multimedia content can also be performed in accordance with the Real Time Streaming Protocol (RTSP).
HTTP based streaming has the advantage that it re-uses existing Internet infrastructure and is mostly client based. The latter means that HTTP based streaming does not require (substantial) modification of existing HTTP servers. Media files and media description files may be stored on a HTTP server from where an HTTP client fetches the files using HTTP GET commands.
HTTP based streaming solutions are already standardized for the Internet Protocol Multimedia Subsystem (IMS). A video conferencing system based on IMS uses an IMS core network, one or more Application Servers (aSs) in the control plane, and a Media Resource Function (MRF) in the user plane for conference bridges or media transcoding. A common term for a conference bridge is Multipoint Control Unit (MCU).
Due to the use of streaming technologies (which are usually based on live data streams), a user who joins an ongoing video conference may not be able to easily inform himself about the history of the video conference at the time of joining the video conference.